[PATCH v2 0/4] ACPI/PCC: Correct PCC OperationRegion handling

Hi,

This series corrects the handling of PCC OperationRegions and their
shared memory.

ACPI 6.3 states that a PCC OperationRegion describes the shared memory
following the PCC signature. Consequently, COMMAND fields at raw shared
memory offsets 4 and 12 appear at OperationRegion offsets 0 and 8.

The first patch corrects those offsets in ACPICA. This change has already
been submitted upstream:

  https://github.com/acpica/acpica/pull/1205

The ACPICA patch is included here only to document the complete
dependency and aid review and testing. It must enter the kernel through
the ACPICA pull/import process and will not be merged directly through
the Linux ACPI tree.

The remaining Linux patches:

- Preserve the platform-populated PCC signature when copying
  OperationRegion data.
- Release the mailbox channel and region context when ACPICA
  deactivates an OperationRegion.
- Compute and cache the command timeout during channel setup.

There is no strict build dependency in case ACPICA and other 3 changes
need to be merged at different timeline or via different branch.

v1->v2:
 - Updated the commit message to include correct example of PCC Opregion
   as the example added by original commit 77e2a04745ff ("ACPI: PCC:
   Implement OperationRegion handler for the PCC Type 3 subtype")
   incorrectly included the signature as an OperationRegion field.

Regards,
Sudeep

Sudeep Holla (4):
  ACPICA: Fix PCC OperationRegion command offsets
  ACPI: PCC: Preserve shared memory signature in OpRegion handler
  ACPI: PCC: Free channel on OpRegion deactivation
  ACPI: PCC: Cache OpRegion command timeout

 drivers/acpi/acpi_pcc.c       | 55 ++++++++++++++++++++++++++---------
 drivers/acpi/acpica/exfield.c | 11 +++----
 2 files changed, 48 insertions(+), 18 deletions(-)

-- 
2.43.0